Question: $ { \left[\begin{array}{rr}{1} & {2} \\ {3} & {-2}\end{array}\right]-\left[\begin{array}{rr}{-2} & {1} \\ {-1} & {-1}\end{array}\right] = {?} } $
Answer: To find the difference of two matrices, subtract the corresponding items between each matrix. ${\left[\begin{array}{rr}{1}-{-2} & {2}-{1} \\ {3}-{-1} & {-2}-{-1}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{3} & {1} \\ {4} & {-1}\end{array}\right]}$